Malodours may be encountered in the air and on many substrates such as fabrics, hard surfaces, skin, and hair. Their origin may be personal, from sources such as sweat, urine, and faeces, or environmental, from sources such as gasoline, cooking, and tobacco smoke.
Examples of typical malodourous materials include indole, skatole, and methanethiol found in toilet and animal odours; piperidine and ammonia found in urine; pyridine and trimethylamine found in kitchen and garbage odours; hydrogen sulfide, nicotine, and various pyrroles found in cigarette smoke odours; and short chain fatty acids in axillary malodours.
Prior art approaches used to combat or neutralise malodours include superimposing the malodour with a pleasant stronger odour (i.e. odour masking), cross-adaptation by blocking of the malodour olfactory receptors, suppression of the malodour by mixing with an ingredient that causes a negative deviation of Raoult's law (thereby reducing its partial pressure in air), elimination of the malodour by chemical reaction, absorption of the malodour by a porous or cage-like structure, and avoidance of the formation of malodours by such routes as antimicrobials and enzyme inhibitors. Fragrances may be formulated to be particularly effective in reducing the generation and perception of human body odour. Thus, EP 0545556, U.S. Pat. No. 4,304,679, U.S. Pat. No. 4,906,454, EP 0003172 and EP 0005618 all disclose perfume compositions useful for delivering or enhancing deodorant efficacy, either when applied to human skin directly using a cosmetically acceptable vehicle, or when included in a laundry detergent or fabric treatment product. However, these prior art compositions are not designed to be highly effective on malodours that do not come from bacterial sources, such as cigarette smoke or cooking smoke odours.
Examples of materials have that have been shown to have malodour combating properties include those disclosed by Nogami et al. in WO 98/56337 (amber and musk) and by Schleppnik et al. in U.S. Pat. No. 4,622,221 (cyclohexyl alcohols and ester derivatives), U.S. Pat. No. 4,187,251 (alkyl cyclohexyl alkyl ketones), U.S. Pat. No. 4,310,512 (derivatives of acetic and propionic acids) and U.S. Pat. No. 4,009,253 (4-cyclohexyl-4-methyl-2-pentanone); and by Kulka in U.S. Pat. No. 3,074,891 (esters of alpha-, beta-unsaturated monocarboxylic acids) and U.S. Pat. No. 3,077,457 (fumaric acid esters). These materials, however, are not capable of neutralizing all types of functional groups contained in malodour molecules.
All of the above mentioned documents are hereby incorporated by reference as if recited in full herein.
A distinction is generally made between “masking” and “counteracting” an odour. The term “masking” indicates that a fragrance, usually having a pleasant odour, is introduced. The intensity of the odour from the masking fragrance covers or modifies the objectionable odour or is so intense that it renders the objectionable odour imperceptible. The term “counteracting” indicates that the perceived intensity of the objectionable odour is lower or undetectable in the presence of the counteracting agent. The difference is that a counteracting substance may be used at concentrations that do not overwhelm odour perception and may in fact contribute little or no odour, though it reduces or eliminates the perception of the disagreeable odour. The compositions of this invention may provide both masking and counteracting effects in any given application.
The prior art approaches to malodour reduction remain deficient because they provide only limited options for malodour reduction. Accordingly, there is an ongoing need for additional and improved malodour reducing compositions.